Six 8-oxoprotoberberines were synthesized collectively in four steps with acceptable yields (14–19%), of which the products 8-oxopalmatine, 8-oxopseudopalmatine, 8-oxoberberine, and 8-oxopseudoberberine come from nature. The synthetic route was featured with the In(OTf)₃-catalyzed cyclization and Heck coupling. Moreover, the syntheses of the natural products berberine, canadine, and iambertine were achieved via various reductions from 8-oxoberberine, which provided a concise approach to the syntheses of this kind of alkaloids.

中文翻译：

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通过顺序 In(OTf)3 催化环化和 Pd(OAc)2 催化 Heck 偶联集体合成 8-Oxoprotoberberines

共分四步合成了 6 种 8-氧代原小檗碱，收率可接受 (14-19%)，其中产物 8-氧代棕榈碱、8-氧代假小檗碱、8-氧代小檗碱和 8-氧代假小檗碱来自自然界。该合成路线以In(OTf) ₃催化环化和Heck偶联为特点。此外，通过8-氧代小檗碱的各种还原反应，合成了天然产物小檗碱、加拿大黄连素和黄柏碱，为这类生物碱的合成提供了一种简洁的方法。